I usually buy pre-fried tofu (abura-age) to make this, as it absorbs a lot of sauce and is soft and chewy.

For a 4 oz package of abura-age:

2 Tbsp sugar

2 Tbsp mirin

1 Tbsp water

1 Tbsp soy sauce

1 Tbsp green onion

1/2 tsp minced garlic

dash of white pepper

dash of MSG (optional)

Chop the tofu into thin strips and put aside. Chop the green onion into thin rounds and put aside.

Heat the sugar and water until it just starts to turn light golden brown. Add the green onion and garlic (careful, it may sputter), and then quickly add the mirin and soy sauce. Sprinkle in white pepper and MSG if using. Let simmer for about 30 seconds, then add the tofu. Stir until all of the tofu is coated, and simmer a bit longer until some but not all of the tofu is crispy. You can add a little pickled daikon & carrot here if you like.

Use this as the filling for your BanhMi, or anything else that seems tasty.